Family CHYDORIDAE Dybowski & Grochowski, 1894

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Family CHYDORIDAE Dybowski & Grochowski, 1894

Chydorinae Dybowski, B. & Grochowski, M. 1894. O Lynceidach czyli Tonewkach fauny krajowej. Kosmos (Warsaw) A Biologia 19: 376-383 [383[8]] (https://rcin.org.pl/ibd/dlibra/publication/90161/edition/68950) [original spelling].
Type genus:
Chydorus Leach, 1816.
Chydoridae Dybowski & Grochowski, 1894.
Aloninae Frey, D.G. 1967. Phylogenetic relationships in the family Chydoridae (Cladocera). pp. 30-37 in Proceedings of the Symposium on Crustacea held at Ernakulam from January 12 to 15, 1965. Part 1. Mandapam Camp : Marine Biology Association of India,. [https://www.mbai.org.in/uploads/publications/Proceedings%20of%20the%20Symposium%20on%20Crustacea%20Part%20-%20I_1918346778_2024-05-10_10-50-34.pdf] [36] [subjective synonym].
Type genus:
Alona Baird, 1843.

Introduction

Smirnov & Timms (1983) who provided keys to all Australian species recognised four subfamilies, Aloninae Frey, 1967, Chydorinae Stebbing, 1902 [sic.], Eurycercinae Kurz, 1875 and Sayciinae Frey, 1967. The first two are not recognised in this treatment. Eurycercidae is now considered to be of family rank but does not occur in Australia. The genus Eurycercus is listed here only to include two nomina dubia. Sayciidaet is also regarded as having family status. Smirnov & Timms (1983) attributed Chydoridae to Stebbing (1902) but Dybowski & Grochowski's (1894) Chydorinae includng Chydorus predates this author.

Artem Sinev (pers. comm. 23 Dec 2024) provided useful suggestions concerning generic placements and misidentifications.

Diagnosis

Body completely enclosed by a shell and head shield. The latter projects over the bases of antennules as a rostrum and laterally over the bases of the antennae as fornices. Antennules single-jointed, more or less movable, generally not extending beyond tip of rostrum. Both rami of antennae 3-jointed. Antennal formula either 0-0-3/0-1-3 or 0-0-3/1-1-3. Labrum with expanded flattened plate projecting ventrally. Five (sometimes 6) pairs of thoracic limbs, the first 2 pairs more or less prehensile, the next 3 pairs flattened, the 6th if present usually vestigial. Postabdomen strongly compressed laterally, usually provided with teeth or denticles along the dorsal margin and with bundles of movable or non-movable setae lateral to these. Ocellus always present, compound eye usually so. Male is smaller than female, with a special seta on the antennules and a strong copulatory hook on the first pair of thoracic limbs; it also generally exhibits a marked reduction of denticles and setae on the postabdomen and often a marked change in shape of the postabdomen from the condition in the female. An ephippium is produced but is weakly developed.